Biomedical subjects

Steren Chabert

Publications and source records attributed to Steren Chabert.

2 recordsLinked to original sources

PubMed2005

Diffusion tensor imaging of the human optic nerve using a non-CPMG fast spin echo sequence.

PURPOSE: To investigate the diffusion tensor properties of the human optic nerve in vivo using a non-Carr-Purcell-Meiboom-Gill (CPMG) fast spin echo (FSE) sequence. MATERIALS AND METHODS: This non-CPMG FSE sequence, which is based on a quadratic phase modulation of the refocusing pulses, allows diffusion measures to be acquired with full signal and without artifacts from geometric distortions due to magnetic field inhomogeneities, which are among the main problems encountered in the orbital area. RESULTS: Good-quality images were obtained at a resolution of 0.94 x 0.94 x 3 mm. The mean diffusivity (MD) and fractional anisotropy (FA) were respectively 1.1 +/- 0.2 x 10(-3) mm(2)/second and 0.49 +/- 0.06, reflecting the optic nerve anisotropy. CONCLUSION: This non-CPMG-FSE sequence provides reliable diffusion-weighted images of the human optic nerve. This approach could potentially improve the diagnosis and management of optic nerve diseases or compression, such as optic neuritis, orbit tumors, and muscle hypertrophy.

Algorithms↗

PubMed2002

Intramyocardial pressure measurements in the stage 18 embryonic chick heart.

Intramyocardial pressure (IMP) and ventricular pressure (VP) were measured in the trabeculating heart of the stage 18 chick embryo (3 days of incubation). Pressure was measured at several locations across the ventricle using a fluid-filled servo-null system. Maximum systolic and minimum diastolic IMP tended to be greater in the dorsal wall than in the ventral wall, but transmural distributions of peak active (maximum minus minimum) IMP were similar in both walls. Peak active IMP near midwall was similar to peak active VP, but peak active IMP in the subepicardial and subendocardial layers was four to five times larger. These results suggest that the passive stiffness of the dorsal wall is greater than that of the ventral wall and that during contraction the inner and outer layers of both walls generate more contractile force and/or become less permeable to flow than the middle part of the wall. Measured pressures likely correspond to regional variations in wall stress that may influence morphogenesis and function in the embryonic heart.

Animals↗